This invention is generally directed to toner compositions, and more specifically, the present invention relates to toner and developer compositions comprised of novel crosslinked thermotropic crystalline components. More specifically, in one embodiment of the present invention there are provided developer compositions formulated by admixing toner compositions containing crosslinked, or branched thermotropic liquid crystalline polymers, and carrier components. In one specific embodiment of the present invention, there are provided low melting toner compositions with the thermotropic liquid crystalline polymers as illustrated in U.S. Pat. No. 4,543,313, the disclosure of which is totally incorporated herein by reference, which polymers have been crosslinked, or are branched as indicated herein. The toner compositions of the present invention possess a number of advantages including enablement of their melting over a narrow temperature interval wherein there is a substantial decrease in the melt viscosity, which is above the melting temperature of many known toner resins, excellent flow properties, and low fusing temperatures such as, for example, 129.degree. C. thereby enabling less fusing energy and prolonging the fuser life. Specifically, the toner compositions of the present invention possess low fusing temperatures, and therefore lower fusing energies are required for fixing thus enabling less power consumption during fusing, and permitting extended lifetimes for the fuser systems selected. Accordingly, thus the toners of the present invention can be fused (fuser roll set temperature) at temperatures of 275.degree. F. and as low as 225.degree. F. as compared to many currently commercially available toners, which fuse at temperatures of from about 300.degree. F. to about 325.degree. F. Furthermore, the toner compositions of this invention possess a broad fusing lattitude of above 30.degree. C. and as high as 60.degree. C. or more, which inhibits the toner from offsetting onto the fused rollers usually associated with ghosting or background images on subsequent copies. Also, the toner compositions of the present invention possess acceptable blocking characteristics at, for example, above 55.degree. C., thereby avoiding, or substantially minimizing agglomerate during manufacturing, transportation or storage. Moreover, the toner and developer compositions of the present invention are particularly useful in electrophotographic imaging and printing systems, especially xerographic imaging and printing processes.
The electrostatographic process, and particularly the xerographic process, is well known. This process involves the formation of an electrostatic latent image on a photoreceptor, followed by development, and subsequent transfer of the image to a suitable substrate. Numerous different types of xerographic imaging processes are known wherein, for example, insulative developer particles or conductive toner compositions are selected depending on the development systems used. Moreover, of importance with respect to the aforementioned developer compositions are the appropriate triboelectric charging values associated therewith, as it is these values that enable continued constant developed images of high quality and excellent resolution, and admixing characteristics. Specifically, thus toner and developer compositions are known, wherein there are selected as the toner resin styrene acrylates, styrene methacrylates, and certain styrene butadienes, including those available as Pliolites. Other resins have also been selected for incorporation into toner compositions inclusive of the polyesters as illustrated in U.S. Pat. No. 3,590,000. Additionally, it is known that single component magnetic toners can be formulated with styrene butadiene resins, particularly those resins available as Pliolite. In addition, positively charged toner compositions containing various resins, inclusive of certain styrene butadienes and charge enhancing additives, are known. For example, there are described in U.S. Pat. No. 4,560,635, the disclosure of which is totally incorporated herein by reference, positively charged toner compositions with distearyl dimethyl ammonium methyl sulfate charge enhancing additives.
Numerous patents are in existance that illustrate toner compositions with various types of toner resins including, for example, U.S. Pat. Nos. 4,104,066, polycaprolactones; 3,547,822, polyesters; 4,049,447, polyesters; 4,007,293, polyvinyl pyridine-polyurethane; 3,967,962, polyhexamethylene sebaccate; 4,314,931, polymethyl methacrylates; Re. 25,136, polystyrenes; crosslinked toner resins, reference U.S. Pat. No. 3,938,992, Re. 31,071; 4,469,770, styrene butadienes; thermotropic liquid crystalline polycarbonates, copolycarbonates, polyurethanes, polyesters, and copolyesters, reference U.S. Pat. No. 4,543,313, the disclosure of which is totally incorporated herein by reference; and U.S. Pat. No. 4,891,293, the disclosure of which is totally incorporated herein by reference. The thermotropic liquid crystalline polymers of the present invention are similar in some embodiments to those as illustrated in the aforementioned. '313 patent and '293 patent with the important exceptions that the polymers of the present invention are crosslinked, branched, or comprised of a mixture of crosslinked and branched polymers. This enables advantages such as toners exhibiting low melt or low fixing temperatures of, for example, from about 105.degree. to 140.degree. C. while maintaining a broad fusing latitude of from about 20.degree. to 45.degree. C. and acceptable blocking temperature of above 55.degree. C.
Also, there is described in U.S. Pat. No. 4,529,680 magnetic toners for pressure fixation wherein the melting point of the polymer is, for example, from 150.degree. to 240.degree. C., and preferably 180.degree. to 230.degree. C. Other patents of background interest include U.S. Pat. Nos. 3,720,617; 3,752,666; 3,788,994; 3,983,045; 4,051,077; 4,108,653; 4,258,116 and 4,558,108.
In addition, several recently issued patents illustrate toner resins including vinyl polymers, diolefins, and the like, reference for example U.S. Pat. No. 4,560,635. Moreover, there are illustrated in U.S. Pat. No. 4,469,770 toner and developer compositions wherein there is incorporated into the toner styrene butadiene resins prepared by emulsion polymerization processes.
As a result of a patentability search, there were selected U.S. Pat. Nos. 4,543,313, mentioned herein; 4,394,498, which discloses particulate thermotropic liquid crystalline polymers; 4,293,627 and 4,588,668, which illustrate the inclusion of polycarboxylic acids and dicarboxylic acids/diopolyester polymerizations for toners; and as background interest 3,272,644; 4,702,945 and 4,713,196.
Furthermore, a number of different carrier particles have been illustrated in the prior art, reference for example the U.S. Pat. No. 3,590,000 mentioned herein; and U.S. Pat. No. 4,233,387, the disclosures of which are totally incorporated herein by reference, wherein coated carrier components for developer mixtures, which are comprised of finely divided toner particles clinging to the surface of the carrier particles, are recited.
Although the above described toner compositions and resins are suitable for their intended purposes, in most instances there continues to be a need for toner and developer compositions containing new resins. More specifically, there is a need for toners which can be fused at lower energies than many of the presently available resins selected for toners. There is also a need for resins that can be selected for toner compositions which are of low cost, nontoxic, nonblocking at temperatures of less than 50.degree. C., jettable, melt fusible with a broad fusing latitude, cohesive above the melting temperature, and triboelectrically chargeable. In addition, there remains a need for toner compositions which can be fused at low temperatures, that is for example 129.degree. C. or less, as compared to many toners presently in commercial use, which require fusing temperatures of about 300.degree. to 325.degree. F., thereby enabling with the compositions of the present invention the utilization of lower fusing temperatures, and lower fusing energies permitting less power consumption during fusing, and allowing the fuser system, particularly the fuser roll selected, to possess extended lifetimes. Another need resides in the provision of developer compositions comprised of the toner compositions illustrated herein, and carrier particles. There also remains a need for toner and developer compositions containing additives therein, for example charge enhancing components, thereby providing positively, or negatively charged toner compositions. Furthermore, there is a need for toner and developer compositions with crosslinked thermotropic liquid crystalline polymers that will enable the generation of solid image areas with substantially no background deposits, and full gray scale production of half tone images in electrophotographic imaging and printing systems. The aforementioned toner and developer compositions can be selected for electrophotographic imaging and printing systems, especially xerographic processes, and wherein, for example, contact or noncontact fusing can be accomplished such as by flash, radiant, with heated ovens, steam, and the like.